Genetic diversity and population genetic structure of wild banana Musa ornata (Musaceae) in Mexico

The wild banana Musa ornata is an inhabitant
of the tropical regions of Mexico characterized by patches
of tropical rainforest. The overexploitation of its habitat
has caused the extinction of several populations affecting
diversity and population genetic structure of remaining
ones. We used microsatellite markers to determine the
genetic diversity and the population’s genetic structure of
all extant populations. The thirty-two microsatellite loci
previously characterized for M. acuminata and M. balbisiana
were tested in M. ornata. Only twelve amplified.
From these seven were polymorphic and were used for
genetic analyses. The Nei’s diversity estimator shows low
levels of genetic diversity (He = 0.263) with a mean of
4.40 alleles per locus. Excess homozygosity was evident in
all populations indicating high levels of inbreeding. FST
pairwise analyses and AMOVA indicated low genetic
differentiation. However, 28 % of private alleles were
registered, suggesting limited gene flow. Genetic distances,
Jaccard’s coefficient and principal component analysis
showed a good correspondence to geographical locations.
The Mantel test performed was not significant. The results
support the hypothesis of recent fragmentation events;
therefore, not enough time has passed to detect differences
between populations. However, it is also likely that results
are caused by factors such as bottleneck, decline in pollinator
populations, self-pollination and/or a tendency
towards clonal reproduction. It is proposed that the preservation
strategy focuses on maintaining all the remaining
populations and ensuring their connectivity, so as to
maintain gene flow and increase the genetic diversity of
this species.